M95010-R datasheet(22/42 Pages) STMICROELECTRONICS

22 / 42 page

Instructions

M95040, M95020, M95010

22/42

6.6

Write to Memory Array (WRITE)

As shown in Figure 12, to send this instruction to the device, Chip Select (S) is first driven

Low. The bits of the instruction byte, address byte, and at least one data byte are then

shifted in, on Serial Data Input (D).

The instruction is terminated by driving Chip Select (S) High after the rising edge of Serial

Clock (C) that latches the last data bit, and before the next rising edge of Serial Clock (C)

occurs anywhere on the bus. In the case of Figure 12, this occurs after the eighth bit of the

data byte has been latched in, indicating that the instruction is being used to write a single

byte. The self-timed Write cycle starts, and continues for a period tWC (as specified in

Table 18 to Table 22), at the end of which the Write in Progress (WIP) bit is reset to 0.

If, though, Chip Select (S) continues to be driven Low, as shown in Figure 13, the next byte

of input data is shifted in. In this way, all the bytes from the given address to the end of the

same page can be programmed in a single instruction.

If Chip Select (S) still continues to be driven Low, the next byte of input data is shifted in, and

is used to overwrite the byte at the start of the current page.

The instruction is not accepted, and is not executed, under the following conditions:

●

if the Write Enable Latch (WEL) bit has not been set to 1 (by executing a Write Enable

instruction just before)

●

if a Write cycle is already in progress

●

if the device has not been deselected, by Chip Select (S) being driven High, at a byte

boundary (after the rising edge of Serial Clock (C) that latches the last data bit, and

before the next rising edge of Serial Clock (C) occurs anywhere on the bus)

●

if Write Protect (W) is Low or if the addressed page is in the region protected by the

Block Protect (BP1 and BP0) bits.

Figure 12.

Byte Write (WRITE) sequence

Depending on the memory size, as shown in Table 6, the most significant address bits are Don’t Care.

AI01442D

3456789 10 11 12 13 14 15 16 17 18 19

A6 A5 A4 A3 A2 A1 A0

20 21 22 23

High Impedance

Instruction

Byte Address

765432

Data Byte

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